JPH0363933B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for injection molding two types of resin compositions having different flows and having good sliding properties on the surface of a molded product. [Prior art] Conventionally, materials with good sliding properties are generally known, such as nylon or polyacetal mixed with molybdenum disulfide or graphite, but these materials themselves have low mechanical strength and are expensive. There is little freedom in material design, including mechanical strength, and it is difficult to use in areas where high torque is applied, and it is expensive, so it has not been possible to replace metal. Furthermore, as techniques for making only the surface slidable, there are methods using a multi-color molding machine, typically a two-color molding machine, and a Sanderschich molding machine, which performs integral molding at the same time with a slight time difference from the same nozzle. [Object of the invention] The present invention solves the narrow degree of freedom in material design when these slidable materials are used alone, and also achieves two
The present invention was achieved as a result of diligent efforts to expose the sliding material only on the surface of the molded product using a general molding machine without relying on special machines such as color molding machines. It is. [Structure of the Invention] The present invention provides a thermoplastic resin composition with a flow rate of 10% compared to the thermoplastic resin composition measured under the same conditions using a Koka type flow tester.
This is an injection molding method characterized by mixing a resin composition with a resin composition that is at least twice as large and has good sliding properties on the surface of a molded article before injection molding, and then molding. Resin compositions with good sliding properties used in the present invention include nylon, polyacetal, polyethylene, polypropylene, ABS, etc.
It is a molding material based on resins such as AS-based, PES-based, PPS-based, PEEK-based, etc. that has a good appearance and can be injected, and the outflow amount is compared to other resins when measured under the same conditions with a Koka type flow tester. Any method is possible as long as the flow is 10 times or more. Further, any resin can be used as long as it has the material properties required for the other resin. [Effects of the Invention] According to the method of the present invention, compared to any resin composition, the flow rate is 10 times or more when measured under the same conditions with a Koka type flow tester, and the molded product surface has good sliding properties. The resin composition is mixed and molded in an arbitrary ratio before injection molding, and the resulting molded product has good surface sliding properties.The following effects can be mentioned. (1) Since it can be molded with a general injection molding machine, there are no restrictions such as the use of special machines such as multi-color molding machines such as two-color molding machines, and Sandersch molding machines. (2) Any resin composition with desired material properties can be used inside the molded product, and material strength,
Free material design is possible, including cost reduction. (3) Furthermore, not only is the cost lower than when using a dedicated machine such as the two-color molding machine in (1), but the molding shrinkage rate is However, according to the method of the present invention, molded products made by injection molding of a resin composition that has good sliding properties within a molded product and one arbitrary composition can be made using two materials. Since the interface between them changes continuously, deformation based on the difference in molding shrinkage rate and sufficient adhesion strength can be achieved. Example A The following two types of materials were mixed before injection molding as shown in Table 1, and a test piece was prepared using a Nikko N-200 injection molding machine, and the surface sliding properties, bending strength, and bending modulus were measured. The physical properties of the materials were compared and measured. According to this, the mechanical strength of the molded product can be improved without reducing the sliding properties of the surface compared to the sliding property alone. All formulations hereinafter are in parts by weight.

[Table] Example B When the following five materials were mixed as shown in Table 2 and evaluated in exactly the same manner as in Example 1, the fluidity of the sliding material and the other material was A flow tester shows that a difference of at least 10 times is required.

[Table] Example C When the following four materials were mixed as shown in Table 3 and evaluated in exactly the same manner as in Example 1, it was found that the material strength could be freely designed as the material inside the molded product.

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Claims (1)

[Claims] 1. Before injection molding, mix a thermoplastic resin composition with a resin composition that has a flow rate of 10 times or more when measured under the same conditions with a Koka type flow tester and has good sliding properties on the surface of the molded product. , and then molding.